Meta-Analysis Results Using a Random Effects Model: Risk of Basal Cell Carcinoma Associated

Table S1a

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with red and blond versus dark hair colour

Red vs. Dark / Blond vs. Dark
Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het
All studies / 13 / 2.02 (1.68, 2.44) / 32.2 / 0.125 / 12 / 1.38 (1.12, 1.71) / 71.6 / 0.000
Study design
Cohort / 4 / 1.79 (1.50, 2.13) / 33.6 / 0.211 / 3 / 1.38 (0.94, 2.03) / 92.0 / 0.000
Case-control / 9 / 2.63 (1.94, 3.57) / 2.1 / 0.417 / 9 / 1.38 (1.07, 1.78) / 39.8 / 0.102
Study type
Clinic/hospital based / 6 / 3.79 (2.46, 5.86) / 0.0 / 0.753 / 5 / 1.50 (0.97, 2.32) / 44.7 / 0.124
Population based / 6 / 1.83 (1.61, 2.07) / 0.0 / 0.446 / 6 / 1.34 (1.00, 1.81) / 83.8 / 0.000
Clinic/hospital & Population based / 1 / 1.58 (0.69, 3.62) / - / - / 1 / 1.29 (0.93, 1.78) / - / -
Study location
Australia / 2 / 1.81 (1.20, 2.72) / 0.0 / 0.991 / 1 / 1.47 (0.88, 2.46) / - / -
North America / 5 / 1.93 (1.49, 2.50) / 51.6 / 0.082 / 5 / 1.36 (0.94, 1.97) / 84.8 / 0.000
South America / - / - / - / - / - / - / - / -
Northern Europe / 1 / 1.2 (0.11, 13.09) / - / - / 1 / 0.90 (0.29, 2.75) / - / -
Western Europe / 2 / 2.83 (1.33, 6.05) / 73.8 / 0.051 / 2 / 1.38 (0.89, 2.13) / 61.0 / 0.109
Southern Europe / 3 / 2.41 (0.91, 6.35) / 18.4 / 0.294 / 3 / 1.50 (0.83, 2.73) / 67.9 / 0.044
Other / - / - / - / - / - / - / - / -
Year of publication
Before 2000 / 8 / 1.72 (1.38, 2.15) / 9.1 / 0.359 / 8 / 1.21 (1.02, 1.42) / 13.3 / 0.326
After 2000 / 5 / 2.33 (1.76, 3.09) / 33.2 / 0.200 / 4 / 1.72 (1.17, 2.52) / 81.4 / 0.001
Method of assessment
Observed / 6 / 2.29 (1.59, 3.29) / 35.2 / 0.173 / 4 / 1.14 (0.85, 1.54) / 30.2 / 0.231
Self reported / 7 / 1.88 (1.53, 2.32) / 29.4 / 0.204 / 8 / 1.53 (1.17, 2.00) / 77.4 / 0.000
Adjusted for skin colour/type
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 7 / 1.84 (1.50, 2.25) / 25.9 / 0.231 / 7 / 1.26 (0.94, 1.69) / 80.0 / 0.000
No / 6 / 2.42 (1.69, 3.46) / 32.2 / 0.194 / 5 / 1.57 (1.11, 2.21) / 50.9 / 0.086
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 1 / 1.46 (1.15, 1.86) / - / - / 1 / 1.13 (0.94, 1.35) / - / -
No / 12 / 2.10 (1.83, 2.42) / 34.6 / 0.105 / 11 / 1.42 (1.13, 1.79) / 65.7 / 0.001

Table S1b

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with red/blond and light brown versus dark hair colour

Red/Blond vs. Dark / Light brown vs. Dark
Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het
All studies / 10 / 1.69 (1.24, 2.29) / 84.5 / 0.000 / 11 / 1.27 (1.06, 1.53) / 67.6 / 0.001
Study design
Cohort / - / - / - / - / 2 / 1.39 (0.96, 2.02) / 91.9 / 0.000
Case-control / 10 / 1.69 (1.24, 2.29) / 84.5 / 0.000 / 9 / 1.22 (0.97, 1.54) / 50.8 / 0.039
Study type
Clinic/hospital based / 7 / 1.68 (1.16, 2.41) / 70.0 / 0.003 / 5 / 1.28 (0.84, 1.94) / 60.7 / 0.038
Population based / 3 / 1.72 (1.01, 2.91) / 85.1 / 0.001 / 5 / 1.30 (1.0, 1.68) / 79.1 / 0.001
Clinic/hospital & Population based / - / - / - / - / 1 / 1.20 (0.89, 1,61) / - / -
Study location
Australia / 1 / 2.30 (1.38, 3.83) / - / - / 1 / 1.15 (0.82, 1.61) / - / -
North America / 2 / 1.84 (0.73, 4.63) / 97.4 / 0.000 / 5 / 1.31 (0.99, 1.73) / 77.5 / 0.001
South America / 2 / 1.06 (0.71, 1.59) / 0.0 / 0.622 / - / - / - / -
Northern Europe / 1 / 1.61 (1.02, 2.53) / - / - / - / - / - / -
Western Europe / 1 / 2.17 (1.29, 3.32) / - / - / 1 / 1.74 (1.14, 2.66) / - / -
Southern Europe / 2 / 1.50 (0.96, 2.32) / 0.0 / 0.326 / 4 / 1.15 (0.76, 1.74) / 63.2 / 0.043
Other / 1 / 2.05 (1.06, 3.98) / - / - / - / - / - / -
Year of publication
Before 2000 / 7 / 1.70 (1.17, 2.45) / 87.9 / 0.000 / 7 / 1.18 (1.01, 1.38) / 31.8 / 0.185
After 2000 / 3 / 1.68 (0.86, 3.27) / 66.5 / 0.050 / 4 / 1.44 (0.97, 2.14) / 67.4 / 0.027
Method of assessment
Observed / 1 / 1.37 (0.85, 2.20) / - / - / 4 / 1.08 (0.90, 1.30) / 1.7 / 0.384
Self reported / 9 / 1.73 (1.23, 2.44) / 86.1 / 0.000 / 7 / 1.45 (1.13, 1.86) / 72.1 / 0.001
Adjusted for skin colour/type
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 1 / 2.60 (0.79, 8.52) / - / - / 7 / 1.16 (0.92, 1.45) / 75.4 / 0.000
No / 9 / 1.65 (1.21, 2.26) / 85.8 / 0.000 / 4 / 1.63 (1.12, 2.36) / 45.9 / 0.136
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 2 / 2.34 (1.47, 3.75) / 0.0 / 0.853 / 2 / 0.87 (0.40, 1.88) / 66.3 / 0.085
No / 8 / 1.59 (1.14, 2.22) / 86.1 / 0.000 / 9 / 1.35 (1.10, 1.66) / 61.4 / 0.008

Table S2

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with eye colour

Blue/Blue-grey vs. Dark / Green/Green-grey-hazel vs. Dark / Blue-grey/Green-hazel vs. Dark
Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het
All studies / 18 / 1.68 (1.37, 2.07) / 84.2 / 0.000 / 15 / 1.61 (1.35, 1.92) / 66.9 / 0.000 / 4 / 1.58 (1.16, 2.13) / 35.4 / 0.200
Study design
Cohort / 3 / 1.16 (0.91, 1.47) / 56.1 / 0.127 / 1 / 1.19 (1.07, 1.32) / - / - / - / - / - / -
Case-control / 15 / 1.78 (1.42, 2.25) / 79.4 / 0.000 / 14 / 1.68 (1.39, 2.03) / 55.4 / 0.006 / 4 / 1.58 (1.16, 2.13) / 35.4 / 0.200
Study type
Clinic/hospital based / 9 / 2.23 (1.69, 2.94) / 67.1 / 0.002 / 9 / 1.97 (1.48, 2.61) / 57.7 / 0.015 / 4 / 1.58 (1.16, 2.13) / 35.4 / 0.200
Population based / 8 / 1.20 (1.04, 1.38) / 34.3 / 0.154 / 5 / 1.22 (1.11, 1.34) / 0.0 / 0.624 / - / - / - / -
Clinic/hospital & Population based / 1 / 1.35 (1.09, 1.67) / - / - / 1 / 1.37 (1.15, 1.64) / - / - / - / - / - / -
Study location
Australia / 2 / 1.28 (0.73, 2.34) / 68.1 / 0.077 / 2 / 1.36 (0.90, 2.05) / 30.2 / 0.231 / - / - / - / -
North America / 7 / 1.69 (1.18, 2.44) / 91.4 / 0.000 / 5 / 1.55 (1.16, 2.07) / 70.1 / 0.010 / - / - / - / -
South America / - / - / - / - / - / - / - / - / 2 / 1.22 (0.84, 1.77) / 0.0 / 0.626
Northern Europe / 1 / 0.80 (0.29, 2.22) / - / - / 1 / 1.10 (0.39, 3.11) / - / - / 1 / 1.71 (1.23, 2,37) / - / -
Western Europe / 3 / 1.73 (0.94, 3.18) / 85.0 / 0.001 / 2 / 1.60 (1.13, 2.26) / 0.0 / 0.500 / - / - / - / -
Southern Europe / 5 / 2.15 (1.36, 3.40) / 74.4 / 0.004 / 5 / 2.07 (1.30, 3.30) / 80.9 / 0.000 / - / - / - / -
Other / - / - / - / - / - / - / - / - / 1 / 2.57 (1.37, 4.82) / - / -
Year of publication
Before 2000 / 12 / 1.55 (1.22, 1.99) / 85.5 / 0.000 / 10 / 1.54 (1.26, 1.89) / 70.8 / 0.000 / 3 / 1.70 (1.24, 2.33) / 32.8 / 0.226
After 2000 / 6 / 2.01 (1.32, 3.07) / 78.8 / 0.000 / 5 / 1.79 (1.37, 2.34) / 20.2 / 0.286 / 1 / 1.07 (0.56, 2.03) / - / -
Method of assessment
Observed / 12 / 1.92 (1.44, 2.55) / 78.7 / 0.000 / 11 / 1.73 (1.36, 2.20) / 62.7 / 0.003 / 1 / 1.07 (0.56, 2.03) / - / -
Self reported / 6 / 1.38 (1.09, 1.75) / 78.5 / 0.000 / 4 / 1.42 (1.09, 1.85) / 61.8 / 0.049 / 3 / 1.70 (1.24, 2.33) / 32.8 / 0.226
Adjusted for skin colour/type
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 5 / 1.31 (1.06, 1.62) / 61.5 / 0.034 / 5 / 1.36 (1.15, 1.61) / 51.2 / 0.085 / 1 / 1.07 (0.56, 2.03) / - / -
No / 13 / 1.92 (1.44, 2.55) / 83.4 / 0.000 / 10 / 1.82 (1.38, 2.40) / 61.8 / 0.005 / 3 / 1.70 (1.24, 2.33) / 32.8 / 0.226
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 3 / 1.57 (0.90, 2.72) / 71.0 / 0.032 / 1 / 1.19 (1.07, 1.32) / - / - / - / - / - / -
No / 16 / 1.72 (1.36, 2.16) / 81.7 / 0.000 / 14 / 1.68 (1.39, 2.03) / 55.4 / 0.006 / 4 / 1.58 (1.16, 2.13) / 35.4 / 0.200

Table S3

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with skin colour

Fair/Light vs. Dark/Olive / Medium vs. Dark/Olive
Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het
All studies / 12 / 2.11 (1.56, 2.86) / 83.0 / 0.000 / 6 / 1.37 (0.90, 2.09) / 59.5 / 0.030
Study design
Cohort / 1 / 2.0 (1.18, 3.39) / - / - / 1 / 0.98 (0.54, 1.76) / - / -
Case-control / 11 / 2.14 (1.54, 2.95) / 84.1 / 0.000 / 5 / 1.51 (0.90, 2.54) / 65.7 / 0.020
Study type
Clinic/hospital based / 9 / 2.27 (1.54, 3.35) / 81.1 / 0.000 / 4 / 1.22 (0.82, 1.81) / 41.1 / 0.165
Population based / 3 / 1.80 (0.98, 3.29) / 76.8 / 0.013 / 2 / 2.04 (0.43, 9.65) / 85.3 / 0.009
Study location
Australia / 1 / 2.00 (1.18, 3.39) / - / - / 1 / 0.98 (0.54, 1.76) / - / -
North America / 6 / 1.73 (1.22, 2.46) / 83.7 / 0.000 / 2 / 1.84 (0.32, 10.77) / 88.8 / 0.003
South America / - / - / - / - / - / - / - / -
Northern Europe / - / - / - / - / - / - / - / -
Western Europe / - / - / - / - / - / - / - / -
Southern Europe / 5 / 3.01 (1.43, 6.33) / 82.1 / 0.000 / 3 / 1.40 (0.94, 2.09) / 21.4 / 0.280
Year of publication
Before 2000 / 9 / 1.75 (1.32, 2.33) / 78.3 / 0.000 / 5 / 1.35 (0.84, 2.15) / 66.4 / 0.018
After 2000 / 3 / 3.72 (2.56, 5.41) / 0.0 / 0.629 / 1 / 1.74 (0.61, 4.98) / - / -
Method of assessment
Observed / 8 / 2.17 (1.54, 3.05) / 63.9 / 0.007 / 6 / 1.37 (0.90, 2.09) / 59.5 / 0.030
Self reported / 4 / 2.02 (1.17, 3.47) / 90.3 / 0.000 / - / - / - / -
Adjusted for skin type
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 4 / 2.81 (1.28, 6.15) / 85.2 / 0.000 / 2 / 2.12 (0.50, 8.91) / 85.0 / 0.010
No / 8 / 1.84 (1.35, 2.52) / 79.1 / 0.000 / 4 / 1.20 (0.76, 1.88) / 44.0 / 0.148
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 1 / 4.90 (2.40, 10.0) / - / - / - / - / - / -
No / 11 / 1.95 (1.46, 2.62) / 81.1 / 0.000 / 6 / 1.37 (0.90, 2.09) / 59.5 / 0.030

Table S4

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with skin phototype

Skin phototype I/II vs. III/IV
Studies / OR (95% CI) / I2 (%) / P het
All studies / 9 / 1.70 (1.17, 2.47) / 83.3 / 0.000
Study design
Cohort / - / - / - / -
Case-control / 9 / 1.70 (1.17, 2.47) / 83.3 / 0.000
Study type
Clinic/hospital based / 8 / 1.65 (1.02, 2.66) / 85.4 / 0.000
Population based / 1 / 1.86 (1.48, 2.34) / - / -
Study location
Australia / - / - / - / -
North America / 2 / 1.90 (1.53, 2.35) / 0.0 / 0.631
South America / 2 / 2.59 (1.80, 3.70) / 0.0 / 0.484
Northern Europe / 2 / 1.77 (1.22, 2.57) / 0.0 / 0.584
Western Europe / 1 / 3.50 (2.47, 4.95) / - / -
Southern Europe / 2 / 0.53 (0.14, 1.97) / 88.0 / 0.004
Year of publication
Before 2000 / 5 / 1.99 (1.68, 2.36) / 0.0 / 0.465
After 2000 / 4 / 1.21 (0.43, 3.40) / 93.2 / 0.000
Method of assessment
Observed / - / - / - / -
Self reported / 9 / 1.70 (1.17, 2.47) / 83.3 / 0.000
Adjusted for skin colour
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 2 / 0.74 (0.10, 5.75) / 93.4 / 0.000
No / 7 / 2.05 (1.52, 2.57) / 71.5 / 0.002
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 2 / 0.87 (0.09, 8.96) / 96.4 / 0.000
No / 7 / 1.95 (1.45, 2.64) / 68.2 / 0.004

Table S5

Meta-analysis results using a random effects model: Risk of basal cell carcinoma associated with tanning/burning

‘Tan/rarely burn’ vs. ‘tan never burn’ / ‘Often burn then tan’ vs. ‘tan never burn’ / ‘Burn never tan’ vs. ‘ tan never burn’
Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het / Studies / OR (95% CI) / I2 (%) / P het
All studies / 5 / 1.69 (1.27, 2.25) / 69.7 / 0.010 / 8 / 1.55 (1.12, 2.14) / 98.1 / 0.000 / 11 / 2.03 (1.73, 2.38) / 94.4 / 0.000
Study design
Cohort / - / - / - / - / 1 / 1.51 (1.37, 1.67) / - / - / 1 / 2.72 (1.13, 6.55) / - / -
Case-control / 5 / 1.69 (1.27, 2.25) / 69.7 / 0.010 / 7 / 1.54 (1.01, 2.35) / 98.3 / 0.000 / 10 / 2.01 (1.71, 2.37) / 95.0 / 0.000
Study type
Clinic/hospital based / 3 / 2.21 (2.00, 2.43) / 0.0 / 0.768 / 3 / 2.01 (0.98, 4.14) / 99.4 / 0.000 / 6 / 1.93 (1.59, 2.34) / 97.1 / 0.000
Population based / 2 / 1.08 (0.70, 1.69) / 0.0 / 0.975 / 4 / 1.33 (1.07, 1.64) / 44.2 / 0.146 / 4 / 1.98 (1.45, 2.71) / 0.0 / 0.471
Clinic/hospital & Population based / 1 / 1.69 (1.36, 2.11) / - / - / 1 / 1.43 (1.19, 1.72) / - / - / 1 / 2.71 (2.11, 3.48) / - / -
Study location
Australia / - / - / - / - / 1 / 1.38 (0.81, 2.35) / - / - / 1 / 2.63 (1.49, 4.64) / - / -
North America / 2 / 1.49 (0.73, 3.03) / 0.0 / 0.449 / 3 / 1.52 (1.30, 1.78) / 82.9 / 0.003 / 4 / 2.20 (2.07, 2,33) / 67.6 / 0.026
South America / - / - / - / - / - / - / - / - / - / - / - / -
Northern Europe / - / - / - / - / - / - / - / - / - / - / - / -
Western Europe / 1 / 1.08 (0.66,1.76) / - / - / 1 / 1.27 (0.89, 1.81) / - / - / 1 / 1.59 (0.95, 2.66) / - / -
Southern Europe / 2 / 1.97 (1.52, 2.56) / 78.9 / 0.029 / 3 / 1.90 (0.76, 4.73) / 98.8 / 0.000 / 5 / 1.58 (0.65, 3.82) / 97.5 / 0.000
Other / - / - / - / - / - / - / - / - / - / - / - / -
Year of publication
Before 2000 / 3 / 1.42 (1.02, 1.98) / 35.6 / 0.212 / 7 / 1.41 (1.23, 1.60) / 76.6 / 0.000 / 8 / 2.23 (2.09, 2.39) / 60.5 / 0.013
After 2000 / 2 / 2.21 (2.00, 2.43) / 0.0 / 0.768 / 1 / 4.28 (3.88, 4.72) / - / - / 3 / 0.96 (0.12, 7.62) / 98.7 / 0.000
Adjusted for skin colour/type
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / 3 / 1.67 (1.35, 2.06) / 0.0 / 0.709 / 4 / 1.31 (1.09, 1.57) / 64.5 / 0.037 / 4 / 2.62 (2.00, 3.34) / 33.6 / 0.211
No / 2 / 1.61 (0.80, 3.23) / 87.4 / 0.005 / 4 / 1.92 (1.02, 3.62) / 99.1 / 0.000 / 7 / 1.83 (1.51, 2.21) / 96.5 / 0.000
Adjusted for time spent outdoor
2000
Yugoslavia
Clinic/Hospital
200/399





Yes / - / - / - / - / 1 / 1.51 (1.37, 1.67) / - / - / 3 / 3.15 (2.15, 4.63) / 0.0 / 0.488
No / 5 / 1.69 (1.27, 2.25) / 69.7 / 0.010 / 7 / 1.54 (1.01, 2.35) / 98.3 / 0.000 / 8 / 1.90 (1.61, 2.26) / 96.0 / 0.000

Table S6